Protective coating for beryllium metal



United States Patent 3-298 877 PROTECTIVE COATIN Fbn BERYLLIUM METAL Simon J. Morana, Hazleton, Pa., assignor to The Berylllum Corporation, Reading, Pa., a corporation of Delaware No Drawing. Filed Feb. 25, 1963, Ser. No. 260,811 2 Claims. (Cl. 14831.5)

This invention relates to a protective coating for beryllium. More specifically, it deals with a process for coating beryllium to protect it from oxidation at elevated temperatures.

It is an object of the instant invention to produce a beryllium metal having a high degree of oxidation protection.

' Another object of the instant invention is to produce a beryllium metal having a protective coating of titanium suboxide-beryllium oxide complex deposited thereon.

A further object of the instant invention is to produce a protective coating on beryllium by the hydrolytic decomposition of organic titanic esters.

A still further object of the instant invention is to produce a titanium suboxide-beryllium oxide complex coating on beryllium metal which is about one millionth of an inch thick.

Other objects and advantages of the invention will be best understood from a consideration of the following detailed description.

It has been found that thin coatings about one millionth of an inch thick of a titanium complex on the surface of metallic beryllium results in an unexpectedly high degree of oxidationv protection at elevated temperatures.

In the, prior art titanium dioxide coatings have been used to promote adhesion of plastic films, such as polyethylene, nitrocellulose, etc. They have also been used to coat glass, silicones, as water repellants, and in resins and catalysts.

In the present invention coatings are formed on the beryllium metal by hydrolytic decomposition of commercially available organic titanate esters.

The process consists of applying a very thin coat of a titanate ester from a suitable solvent onto a film substrate, beryllium metal being the substrate in the instant case, evaporating the volatile solvent at low relative humidity, then hydrolyzing the titanate esters at normal 50 to 80% humidity. It is believed that the protection is due to a thin covering of a titanium suboxide-beryllium oxide complex (TiOBeO) on the metal surface.

The process is more fully illustrated by the following examples.

Example I A beryllium metal part to be coated was dipped in a 6% solution of tetra isopropyl titanate in hexane. The solution was contained in a chamber maintained at 15 to 18% humidity. The beryllium metal part was slowly withdrawn at a continuous rate of 3 inches per minute, at which time the hexane was distilled from the surface of the metal and the disc was transferred to a chamber above it at room temperature and humidity of at least 50%, where the titanate ester coating hydrolyzed, evaporating the volatile hydrolysis by-products. This resulted in a tenacious hydrophilic titanium suboxide-beryllium oxide complex surface coating.

The above disc of beryllium metal containing a single titanium suboxide-beryllium oxide complex coating was heated in a rnuflle heater in an air atmosphere at 1400 F. for 16 hours.

The disc retained metallic appearance.

3,298,877 Patented Jan. 17, 1967 Example 11 Weight at end 2.3249 grams. Weight at start 2.3195 grams.

Weight gain 0.0054 grams=about .22%.

The disc retained metallic appearance.

Example Ill An uncoated beryllium metal disc was heated in a muffie heater in an air atmosphere at 1400 F. for 16 hours.

Weight at end 5.9553 grams. Weight at start 2.1422 grams.

Weight gain 3.8131 grams=about 2.78%

wt. of metal.

The disc oxidized completely to beryllium oxide powder.

Example IV Another uncoated disc of beryllium metal was heated in a muffle heater in an air atmosphere at 1775 F. for 1 /2 hours.

Weight at end 5.6857 grams. Weight at start 2.3569 grams.

Weight gain 3.3288 grams=141.5% wt.

of metal.

There was a dimensional gain along with the weight gain. After 15 minutes at the temperature the disc began to curl at the edges and ultimately took the form of an exaggerated potato chip curl after about 60 minutes.

Example V A beryllium metal disc was coated according to the procedure of Example I using a 10% solution of tetra isopropyl titanate in hexane and was then heated in a muffle heater in an air atmosphere at 1450 F. for four hours.

Weight at end 2.5698 grams. Weight at start 2.5651 grams.

Weight gain 0.0047 grams=about .18%.

Examples VI, VII, and VIII Three beryllium metal discs were coated according to the procedure of Example I using a 10% solution of partially polymerized butyl titanate in hexane, and then heated in a muflle heater. Table I represents the test results.

Wt. before, g. Wt. after, g. Wt. gain, Time, Temp.,

percent hrs. F.

Example VI. 2.1349 2.1370 0. 09 16 1, 400 Example VII 2. 5237 2. 5293 0. 22 4 1, 450 Example VIII.. 2. 6166 2. 6240 0. 28 1% 1, 775

It was found by experiment that it is necessary to completely hydrolyze the coated part in order to enhance the effectiveness of the elevated oxidation resistance of the coating. For example, two beryllium discs coated at the same timewere subjected to high temperature conditions. I claim: v One disc was hydrolyzed in air for 15 minutes and the 1. A beryllium metal containing a coating of a titanium second disc was hydrolyzed in air for two days prior to suboxide-beryllium oxide complex. subjection to heat. Following are the experimental 2. The metal of claim 1, wherein the coating is one results: 5 millionth of an inch thick.

Type Air Weight Weight Weight coating Hydrolysis Time-Temp. before, g. after, g. gain,

percent Ex. 1V 1hr. at 1775F 2.3234 3.1297 34.5 Uncoated i1 hr. at 1775 F 3.6928 6. 7496 82.7 Ex. IV da S {1% hr. at1775 2.6166 2. 6240 .28 Unc0ated y 1% hr. at 1775 2.3569 5.6857 141. 5

As this invention may be embodied in several forms 15 References Cited by the Examiner without departing from the spirit or essential character- UNITED STATES PATENTS istics thereof, the present embodiment is therefore illustrative and not restrictive, since the scope of the invention 2,768,909 10/1956 Haslam P 2 is defined in the appended claims, and all changes that fall within the metes and bounds of the claims, or that 20 ALFRED LEAVITT Examine? form their functional as well as conjointly cooperative JOSEPH B. SPENCER, RICHARD D. NEVIUS, equivalents, are therefore intended to be embraced by Examiners those claims. I. R. BATTEN. JR.. Assistant Examiners. 

1. A BERYLLIUM METAL CONTAINING A COATING OF A TITANIUM SUBOXIDE-BERYLLIUM OXIDE COMPLEX. 